1. Field
Embodiments of the present invention relate to display devices with touch input devices and, more specifically, systems and methods for reducing display lag between the touch input device and the display device.
2. Related Art
In recent years, touchscreen devices have become commonplace as personal mobile devices, such as mobile phones, tablets, laptops, and the like have gained in popularity. In addition to portable devices, touchscreens are being used in industry and in places such as cars and kiosks where keyboard-and-mouse systems do not allow fast, intuitive, or accurate interaction by the user with a display's content.
Touchscreen displays recognize user input by, for example, sensing touching (or tapping) of the screen, or by sensing a user's fingers or hand gestures in close proximity to the touchscreen. A touchscreen may be any surface onto which an image is projected, and from which a touch can be sensed.
Touch events detected by the touch sensor panels are typically processed by high level application software running on an application processor (AP) of the device. The many processing steps between the touch sensor panel and the AP and the non-deterministic processing time on the AP (including delays due to other computational tasks being performed by the AP, such as running the device's operating system and other applications) introduce high levels of latency (e.g., 70 to 100 milliseconds) that reduce responsiveness of the computing device to the user's touch inputs.
Some empirical studies have indicated that most humans can detect even a 30 millisecond asynchrony between senses, such as touch and vision (see, e.g., Keetels, M. and Vroomen, J. (2012). Perception of Synchrony Between the Senses. In M. M. Murray and M. T. Wallace (Eds.), Frontiers in the neural basis of multisensory processes (pp. 147-177). London: Taylor & Francis Group). Delays of 50 to 200 milliseconds would be detectable to most of users of these computing devices, which can lead to increased user frustration due to the failure of computing the device to immediately provide feedback to the user's input.
However, because the system processor also manages the other processes of the device (e.g., running the device's operating system and many other applications), response time required to update the appearance of the virtual keyboard can be slow, and there may be a noticeable lag between the time the user touches a key and the time that a visual feedback to the key press is provided to the user.